Printed circuit boards are vital components of devices used in many different types of technologies. In fact, the printed circuit board industry is a multi-billion dollar industry that is essential for efficient worldwide manufacturing efforts, the defense industry and electronic based consumer products.
A significant drawback associated with the use of printed circuit boards relates to the manner in which printed circuit boards are usually manufactured. In particular, the common method of manufacturing printed circuit boards utilizes a photoresist masking process. Such a process usually requires that a circuit pattern is transposed onto a film, such as a negative film. A blank circuit board, which may include an insulating layer, such as MYLAR, and a conductive layer, which may include copper, glued to the surface of the insulating layer, is then provided. The conductive surface of the blank circuit board is then exposed to a photoresist composition.
At this time, the film including the circuit pattern thereon is transposed on the photoresist treated circuit board to form an assembly. This assembly is then usually placed in a dark room and exposed to light having light waves of a preselected frequency sufficient to initiate chemical reactions in the exposed areas of the photoresist material. The areas covered by the circuit pattern on the film are not exposed to light and thus do not undergo any additional chemical reactions at this time.
The exposed areas of the photoresist material become bonded to the conductive surface of the printed circuit board. The unexposed areas of photoresist material are then washed off of the printed circuit board with a suitable solution. The remaining pattern of photoresist material on the printed circuit board represents the desired printed circuit pattern to be formed.
An acid-based solution is then applied to the surface of the printed circuit board including the photoresist material and the conductive material. Application of the acid solution etches away all of the exposed conductive material from the surface of the printed circuit board while the areas protected by the photoresist material remain on the surface of the printed circuit board. At this time, the surface of the printed circuit board displays a printed circuit pattern including photoresist material over a conductive pattern and exposed insulated material. Upon completion of the etching process, the printed circuit board is then immersed in a cleaning solution, or cleaned in an otherwise acceptable manner. As a final step, it is often desirable to process the printed circuit board in a wave soldering machine so that a layer of solder is applied to the exposed conductive surface pattern on the printed circuit board. The application of solder as an additional layer on top of the copper layer is desirable because it facilitates soldering electrical components to the printed circuit board during manufacturing operations.
Although the aforementioned process of manufacturing printed circuit boards is widely used, several significant drawbacks exist in connection with such a process. One obvious drawback relates to the use of large amounts of acid and photoresist which need to be disposed of. Additionally, the photoresist masking process requires the use of large amounts of solvents, which also pose a disposal problem. Accordingly, thousand of gallons of toxic solvents and acid-based solutions are used each month to manufacture printed circuit boards in accordance with the photoresist masking process discussed above.
The present invention addresses the shortcomings by providing a flycutting apparatus and a method for manufacturing printed circuit boards without using many of the chemicals associated with the photoresist masking process. To this end, the present invention contemplates using a flycutting machine to manufacture printed circuit boards without the use of hazardous chemicals. Further, the flycutting machine of the present invention may include a sensor to permit automatic or manual adjustment during machining operations to assure that the associated printed circuit boards are being machined to a proper depth.
The flycutting machine of the present invention may be used in various applications other than manufacturing printed circuit boards as disclosed herein. Prior art flycutting machines have been used to manufacture highly reflective surfaces and surfaces that require a high degree of accurate planarization. However, no known flycutting machine includes means for permitting vertical adjustment of the rotatable flycutting disk during machining operations.